Infection with serogroup 2 D-simian retrovirus (SRV) is the cause of most cases of Simian Acquired Immunodeficiency Syndrome (SAIDS) in colonies of Asian macaques. Previously we described the envelope sequence of the D2/RHE/OR isolate (J. Virol 69:2621-2628, 1995). In the past year, we completed genomic sequencing of two distinct SRV 2 family members 18B1 (D2/RHE/OR) and pV1 (D2/RHE/OR/V1). Both of these molecular clones retain prototypical type D genetic structure (5'LTR-gag-prt-pol-env-3'LTR) and encode identically-sized 8105 bp proviruses. 18B-01 and pV1 are 99.3% similar at the amino acid level, exhibiting only 17 residue differences (3, 1, 3 and 10 residue differences in the gag, prt, pol and env genes, respectively). Both clones contain identical LTR and intergenic spacer regions. We constructed two infectious reciprocal virus chimeras by interchanging the 5' and 3' halves of the 18B-1 and pV1 genomes using a conserved Bam HI restriction site in the pol genes. The resulting chimeras segregate the collective amino acid differences in the gag, prt and pol genes from all 10 amino acid residue differences found in the env gene. While pV1 readily infects B-lineage (Raji) and T-lineage (Hut 78) cell lines in vitro using cell-free virus,18B-1 readily infects only Raji cells and will infect Hut 78 cells Interestingly, cell-associated and cell-free virus preparations from both D2/RHE/OR and D2/RHE/OR/V1 macaque isolates can efficiently infect both B- and T-lineage cell lines in vitro, suggesting that the delayed kinetics of cell-free 18B-1 infection of Hut 78 cells may be due to altered interaction with receptor or post entry events. The newly constructed chimeric viruses will be used to examine the potential role of the SRV serogroup 2 env glycoprotein in modulating the differential infection of B- and T-lineage cell lines.